System and method for estimating whether an object hit or missed a target

ABSTRACT

The subject matter discloses a method for estimating hit or miss of an object directed towards a target, comprising collecting an audio signal over time by an audio sensor located on, inside or near the target, said audio signal is defined by a set of frequencies, identifying changes in the set of frequencies over time, predicting a minimal distance between the object and the audio sensor based on the changes in set of frequencies over time, emitting an indication according to the minimal distance between the object and the audio sensor.

FIELD

The present invention relates to estimating whether an object hit ormissed a target.

BACKGROUND

Objects, such as bullets, projectiles, balls, plastics objects, andothers, are many times shot at a target. Such a target may be part of afiring training session, or part of a game, in which a player uses a toygun and fires, shoots, or throws physical objects at a target. Thetarget may be static or movable, for example mounted on a players' upperarm.

It is likely to desire to estimate whether or not the object hit thetarget in order to decide how to reward a player in the game, or toevaluate a training session when firing real projectiles at a target.Current methods to estimate hit or miss include placing a disposablelayer on the target, such as cardboard or paper, and marking the hits onthe disposable layer. This method cannot be used when playing with toyguns, or using objects that do not leave a mark on the target.

SUMMARY

The subject matter discloses a computerized system and method configuredto estimate whether or not an object hits a target or misses a targetbased on audio signals. The object may be a projectile shot from aweapon. The weapon may be a firearm, a training weapon configured tofire non-kill bullets, toys, and the like.

The system comprises one or more audio sensors, such as microphones. Theaudio sensor is electrically coupled to a processing module configuredto process the audio signals, as elaborated below, a digital processorand an indicator configured to indicate whether the object hit or missedthe target. The indicator may be configured to emit the indication inone or more manners, including emitting light, audio, wirelesstransmissions, and vibrations. The indicator emits an indicationaccording to a command from the processing module, the command dependson whether the object hit or missed the target. The system may alsocomprise one or more audio-signal amplifiers.

The system detects objects moving towards the target by sampling sonicand/or ultrasonic and/or infrasonic signals at the processing module'sinput. The system is configured to be placed in or on the target. Incase the system is located inside the target, the audio sensor may beexternal to the target or on its surface, to allow the audio signals toreach them without attenuation. The system tracks the sound emittedduring the objects' movement and detects if the object hit in or on thetarget. The sound may be emitted due to the flow of air or other mediumthrough and around the object, while the object moves through the air orother medium. The system may estimate hit or miss at a sphere-likevolume surrounding the system. The radius of the target around thesystem may be adjusted. Once a hit is detected, the system providesindications using the indicator.

The audio sensor may be configured to collect audio signals in afrequency range that matches a predefined frequency signature of theaudio emitted due to the object's movement. The frequency of the audioemitted due to the object's movement may be stored in the memory unit ofthe system. When the system is configured to determine hits or misses ofmultiple objects having multiple frequency signatures of the audioemitted due to the objects' movements, a specific frequency signatureassociated with a specific object or object type may be inputted intothe system by a user of the system, for example via an input unit of thesystem or by a control interface receiving commands from another device.

The present invention also discloses a method for determining hits ormisses of an object shot at a target. The method comprises collectingthe audio signals by the audio sensor. The audio signals are sampled bythe sensor, for example in a sampling rate of 10,000 samples per second.The audio signals are sent to the processing module. The processingmodule obtains multiple samples of the audio signals emitted due to andduring the object's movement. The processing module may calculate a rateof change in the frequency signature of the audio signals emitted due tothe object's movement.

The invention may be used in the field of toy darts, emitting whistlingnoises while flying through the air. The invention may also be used toanalyze movement of objects in other mediums, such as water. The devicecan be made small enough to be worn on the user's arm, shoulder, neck,or torso, or even pinned or clamped to a piece of clothing. The devicedetects flying darts, and when they hit the wearer inside a certainsphere, circle, or point of impact, the device will indicate a hit, forexample by flashing an LED, emitting specific noises through a smallspeaker, emit vibrations, and send wireless signals to other devices,smart phones, and any other devices participating in the game.

The invention may also be used for the military field of applications,where such devices can be equipped on vehicles, portable targets orpersonnel, capturing whistles of projectiles during combat training. Thecollected signals may be shared or sent to a remote server. The servermay create a map of precise hit points of incoming shells, bullets, andother projectiles.

Another military use case is to use the information of projectiles asthey fly, to create a map of the origin of the shots, allowing to revealthe enemy's location.

It is another object of the subject matter to disclose a method forestimating hit or miss of an object directed towards a target,comprising collecting an audio signal over time by an audio sensorlocated on, inside or near the target, said audio signal is defined by aset of frequencies, identifying changes in the set of frequencies overtime, predicting a minimal distance between the object and the audiosensor based on the changes in set of frequencies over time, emitting anindication according to the minimal distance between the object and theaudio sensor.

In some cases, the method further comprising identifying that the objectis directed towards the target by comparing a pattern from the audiosignal with a list of predefined patterns stored in a computerizedmemory.

In some cases, each of the predefined patterns provides information asto frequencies in which audio is emitted due to the movement of aspecific object, wherein identifying the object based on a frequencypattern associated with the object in the computerized memory.

In some cases, the method further comprising estimating hit or miss of aplurality of different objects having different frequencies.

In some cases, the method further comprising computing a distancebetween the object's hit location and the target and determining a hitor miss of the object in the target by comparing the computed distanceand a threshold distance.

In some cases, computing the distance between the object's hit locationand the target is based on the timing in which the object ended itsmovement, said end of the object's movement is detected when the audiosignal ceases to include the object's frequency signature.

In some cases, the method further comprises defining a range ofdistances from the audio sensor that qualifies as a hit, and determininga hit in case the distance between the hit location and the audio sensoris smaller than the range.

In some cases, the method further comprises defining multiple radii fromthe audio sensor and determining two radii that define the distancebetween the object and the audio sensor.

In some cases, the method further comprises defining a distance betweenthe object and the audio sensor that qualifies as a hit.

In some cases, the method further comprises adjusting the distancebetween the object and the audio sensor that qualifies as a hit based onenvironmental measurements.

In some cases, the method further comprises determining the distancebetween the location in which the object ended its movement and thetarget.

In some cases, the method further comprises detecting that the audiosignal ceases to include the object's frequency signature;

computing a time duration elapsing between a time stamp in which theobject was at the minimal distance from the audio sensor and the time ofdetecting that the audio signal ceases to include the object's frequencysignature;

multiplying the time duration with a known or calculated velocity of theobject.

In some cases, the indication is emitted by at least one of light,sound, RF, and vibration.

In some cases, the method further comprises creating a tracking log,said tracking log comprises the object's location and the detectedfrequencies over time.

In some cases, predicting the minimal distance between the object andaudio sensor is performed before the object reaches the minimaldistance.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced.

In the drawings:

FIG. 1 depicts the system and its comprising elements, in relation to awhistling projectile and the system's whistle detection sphere-likevolume, according to exemplary embodiments of the present invention;

FIG. 2 depicts a projectile entering the hit detection sphere, andending its flight inside that sphere, resulting in a hit indication,according to exemplary embodiments of the present invention;

FIG. 3 depicts a projectile passing inside the hit detection sphere, andending its flight outside that sphere, resulting in a miss indication,according to exemplary embodiments of the present invention;

FIG. 4 depicts a projectile passing outside the hit detection sphere,resulting in a miss indication, according to exemplary embodiments ofthe present invention, according to exemplary embodiments of the presentinvention;

FIG. 5 depicts a person wearing the device in 2 differentconfigurations, according to exemplary embodiments of the presentinvention;

FIG. 6 depicts a dart hit trajectory, according to exemplary embodimentsof the present invention;

FIG. 7 depicts a dart miss trajectory, according to exemplaryembodiments of the present invention;

FIG. 8 depicts a 2D triangulation of hit location from severalmicrophones on the same system, according to exemplary embodiments ofthe present invention;

FIG. 9 depicts a 2D triangulation of hit location from informationshared by several devices, sharing information wirelessly, according toexemplary embodiments of the present invention;

FIG. 10 depicts a special case of a projectile hit and miss, accordingto exemplary embodiments of the present invention;

FIG. 11 shows a graph that shows a shift from the whistle frequency as afunction of the distance from the target, according to exemplaryembodiments of the present invention;

FIG. 12 shows a graph having the system's microphone in the center ofthe graph, showing the percentage of frequency change versus thedistance between the object and the system, according to exemplaryembodiments of the present invention;

FIG. 13 schematically shows an object hitting the target, according toexemplary embodiments of the present invention;

FIG. 14 shows a system for estimating hit or miss of an object based onaudio signals, according to exemplary embodiments of the presentinvention;

FIG. 15 shows a method for estimating hit or miss of an object based onaudio signals, according to exemplary embodiments of the presentinvention;

FIG. 16 shows a method for estimating a change in frequency of the audioemitted due to the object's movement, according to exemplary embodimentsof the present invention.

DETAILED DESCRIPTION

The term “audio signal”, also defined as “frequency spectrum” and“frequency of the audio signal emitted due to and during the object'smovement”, refers to a physical representation of the audio signalgenerated inside a medium, such as air or water, due to and during anobject's movement through that medium, in the sonic and/or ultrasonicand/or infrasonic range.

FIG. 1 depicts the system and its components, in relation to a movingobject and the target, according to exemplary embodiments of the presentinvention. The system is located inside a target, or on a surface of atarget, or very close to the target, for example up to 20 centimetersfrom the target.

The system comprises one or more audio sensors 1, such as microphones,configured to collect audio signals. The audio signals may be in thesonic and/or ultrasonic and/or infrasonic range. The system may befurther comprised of filters and amplifiers 2 configured to enhance theaudio signal collected by the audio sensor, for example to filter theaudio signal in a manner that only the frequency range likely to beemitted by the object during its movement is processed. The system alsocomprises a processing module 3 and an indicator 7. The indicator isconfigured to indicate whether the object hit or missed the target. Theindication may be provided in one or more ways, including emittinglight, audio, wireless transmissions, and vibrations.

In some exemplary cases, the audio sensor provides a digital output,such as microelectromechanical systems MEMS. In such case, the audiosensor may be directly coupled to the digital input of the processingmodule 3. In case the audio sensor comprises analog microphones, themicrophones' output is filtered and amplified, requiring an analogfilter and analog amplifier 2. The filtered analog signal may beconverted to digital format by a standard analog to digital converter(ADC).

Capturing of the digital audio signals may be performed by a DSP orprocessor, via a digital interface. The DSP or processor performsdigital signal processing of the audio signal, in groups of samples, andanalyzes the signal's frequency spectrum and other characteristics.

The system stores the characteristics, for example the frequencyspectrum, of the audio signal. This way, the system is configured toperform a frequency analysis of the collected signals to determinewhether the object is moving towards the system, or has stopped movingor has moved past the system, and to calculate the object's distancefrom the system.

By tracking the object's frequency spectrum over time, group by group ofsamples, the system determines whether the object has ended its movementwithin or without a certain radius from the audio sensor. Changes in theaudio signal are used to predict the minimal distance of the objectduring its movement from the microphone, as detailed below. Aftercalculating the minimal distance between the object and the target, theprocessing module can extract the time stamp in which the object isclosest to the target. The processing module tracks the audio signaluntil the audio generated due to the object's movement ends. Then, theprocessing module extracts the time elapsed between the time stamp inwhich the object is closest to the target and the time stamp in whichthe object's movement ended and calculates the distance between thetarget and the location where the object ended its movement.

It is possible to increase the signal-to-noise-ratio (SNR) of theobject's movement noise, by using more than 1 microphone, and/oractivating noise cancelation techniques on the captured audio signals.This can give better detection chance in noisy environments.

FIG. 2 depicts a projectile entering the hit detection sphere, andending its flight inside that sphere, resulting in a hit indication,according to exemplary embodiments of the present invention.

FIG. 3 depicts a projectile passing inside the hit detection sphere, andending its flight outside that sphere, resulting in a miss indication,according to exemplary embodiments of the present invention.

FIG. 4 depicts a projectile passing outside the hit detection sphere,resulting in a miss indication, according to exemplary embodiments ofthe present invention, according to exemplary embodiments of the presentinvention.

FIG. 5 depicts a person wearing the device in two different ways,according to exemplary embodiments of the present invention. In oneoptional embodiment the system is located on the user's wrist 502 and inanother embodiment, the system is located on the user's chest 501. Thesystem may be embedded in a wearable device, such as a watch, or insidea garment, such as a shirt, hat, or a jacket. The system may be pinnedor clamped to a piece of clothing. Placing multiple systems on the sametarget enables to further enhance the audio signals collected by themultiple systems and processing accuracy of the projectile's movement.Such multiple systems may communicate with each other over a wired orwireless communication channel.

FIG. 6 depicts a dart hit trajectory, according to exemplary embodimentsof the present invention. The figure shows the dart in a first position601, prior to hitting the target area defined by a sphere 603. Thefigure shows the dart in a second position 602, immediately beforehitting the person. The figure also shows the system 604 worn by theperson. The volume of the sphere 603 defines the target. The sphere'svolume may be defined by the user and/or the manufacturer of the system.For example, how far from the system will be considered a hit. One usermay define 5 centimeters and another user will define 25 centimetersfrom the system as a successful hit.

FIG. 7 depicts a dart miss trajectory, according to exemplaryembodiments of the present invention. The figure shows a dart in a firstposition 1, approaching the person wearing the system. The figure alsoshows the same dart in a second position 2, passing in front of theperson. When the dart is in the second position, the minimal distancebetween the dart and the system is lower than the system's threshold ofa “hit”. However, the dart does not end its trajectory inside the sphereand continues its movement towards the third position 3, in which thedart is outside the “hit” distance. The minimal distance of the dartfrom the system is within the “hit” distance, but the “hit” indicationis determined according to the distance between the object and thesystem at the end of the object's movement, which in this case isoutside the “hit” range. The system may provide a “hit” indication only,a “miss” indication only, or both a “hit” indication and a “miss”indication.

FIG. 8 depicts a 2D representation of a triangulation of the hitlocation from several microphones on the same system, according toexemplary embodiments of the present invention. The two-dimensionaltriangulation uses two or more audio sensors 801 and 802. The analysisof the audio signal captured from the two audio sensors 801 and 802define two hit radii 803 and 804 surrounding the respective audiosensor. Combining two such circles resulting from hit radii 803 and 804,produce two points of intersection, 805 and 806, which indicate thepossible hit locations of the object. These points, if inside thedefined hit-detection sphere, will result in a hit indication.Otherwise, it may result in a miss indication. Furthermore, thistriangulation can determine the exact hit location on the target, apartfrom the hit detection itself.

FIG. 9 depicts a 2D representation of a triangulation of hit locationfrom information shared by several devices, sharing informationwirelessly, according to exemplary embodiments of the present invention.In FIG. 9, the audio sensors 902 and 904 define two hit radii 901 and905.

Combining two such circles resulting from hit radii 901 and 905, produce2 points of intersection, 903 and 906, which indicate the possible hitlocations of the object. These points, if inside the definedhit-detection sphere, will result in a hit indication. Otherwise, it mayresult in a miss indication. Furthermore, this triangulation candetermine the exact hit location on the target, apart from the hitdetection itself.

When the system comprises multiple audio sensors, the method ofcalculating the distance from the target may be as follows:

In the first step, the system processes the audio signals from all ofthe multiple audio sensors simultaneously. In the second step, theobject's audio signal is detected by each microphone, and a hit distanceis calculated for each microphone separately. Then, each hit distancecalculated for each microphone is used to simulate a sphere of hitradii, around each microphone's location relative to the othermicrophones. The architecture of microphones is stored in the memoryused by the system, including the location of each microphone relativeto the other microphones. The system then calculates intersection pointsof the multiple simulated spheres surrounding the microphones. Using theintersection points, the system identifies an exact hit location of theobject relative to the system. For example, by computing the distancefrom each microphone and knowing the distances and angles between eachof the microphones. In many cases, more precise results are provided asthe number of microphones is greater.

With two microphones, the hit location will be a 2D circle, whichrepresents an intersection of two spheres. With three microphones, thehit location will be one of two possible 1D points. With fourmicrophones and more, the hit location will be a single possible 1Dpoint. Similarly, this can be accomplished by sharing hit radiiinformation from several separate systems, each having its set of one ormore microphones, with the information shared either by-wire orwirelessly.

FIG. 10 shows a graph representing the frequency change in Hz versus thetime-distance in milliseconds, between the object and the microphone,according to exemplary embodiments of the present invention. The X axisshows the time elapsing and the Y axis shows a change in frequency ofthe audio signal. The graph shows the system's microphone in the centerof the graph, where the value in the Y axis is 0.0.

The graph shows 2 plots of two different objects moving near the systemand their audio signals collected by the system. One plot on the graphis of a hit (orange) and one of miss (blue). Both plots are associatedwith an object flying at 17 m/sec. Both objects emit a sinusoidal audiosignal at about 3000 Hz during their flight. The hit occurs at 50 cmdistance from the microphone, and the miss is a distance greater than150 cm from the microphone.

FIG. 11 shows a graph that shows a shift from the whistle frequency as afunction of the distance from the target, according to exemplaryembodiments of the present invention.

The shift from the whistle frequency has a positive offset when the dartis located in one direction, defined as a positive distance, and has anegative offset when the dart is located in one direction, defined as anegative distance.

FIG. 12 shows a graph having the system's microphone in the center ofthe graph, showing the percentage of frequency change versus thedistance between the object and the microphone, according to exemplaryembodiments of the present invention.

The Y axis shows the minimal distance of the object from the microphone.The X axis shows the advancement of the object from left to right,relative to the microphone.

The graph shows the association between the rate of frequency change dueto the Doppler effect, caused by the velocity of the object relative tothe microphone, which depends on the location of the object at everypoint in time. Also, the graph shows that the closer the minimumdistance of the object to the microphone (along the Y axis), the higherthe rate of frequency change. The amount of frequency change beingfixed, means the duration of the main portion of the frequency changeoccurs in a smaller amount of time, the closer the object's path is tothe microphone.

In some exemplary cases, when the change in the frequency of the audiosignal is higher than a predefined threshold, the minimal distancebetween the object and the target is smaller than a predefined value.Hence, when analyzing the audio signals over time, for example over 0.05seconds, the processing module may predict the minimal distance betweenthe target and the object based on the change in the frequency of theaudio signal over time.

FIG. 13 schematically shows an object hitting the target, according toexemplary embodiments of the present invention. The figure shows aphysical body 1301 functioning as the target. A microphone 1302, oranother audio sensor, is located inside, on or otherwise physically orelectrically connected to the physical body 1301. Line 1303 representsthe minimal distance between the object's closest point 1307 and themicrophone 1302. The object moves from origin 1304, at movement path1305, in the general direction of the physical body 1301. Line 1306represents the distance between the hitting point 1308 of the object andthe microphone 1302. The frequency change is greatest, and its change isimmediate, when the object moves directly towards the microphone 1302,and the frequency change is diminished, and its rate of change decreasesas the minimal distance to the microphone 1302 increases.

FIG. 14 shows a system for estimating hit or miss of an object based onaudio signals, according to exemplary embodiments of the presentinvention. The system comprises an audio sensor 101 configured tocollect audio signals. In some cases, the system comprises multipleaudio sensors. The system also comprises a processing module 102configured to process the collected audio signals and to determinewhether or not the object hit the target. The processing module 102 mayalso determine a minimal distance between the object and the target. Thesystem also comprises an indicator 104 for emitting an indicationaccording to the processor's determination of whether or not the objecthit or missed the target. The system also comprises a memory module 103configured to store a set of rules used by the processor to determinewhether or not the object hit the target. The set of rules may be storedin executable instructions accessed by the processing module whenreceiving a request to determine if the object missed or hit the target.

FIG. 15 shows a method for estimating hit or miss of an object based onaudio signals, according to exemplary embodiments of the presentinvention.

Step 110 discloses collecting audio signal by a sensor. The audiosignals are collected by sampling a frequency range likely to includethe object's characteristic audio signal. For example, objects withdifferent physical forms generate audio signals of different frequencyspectrums as they move through a medium such as air.

Step 120 discloses sending the received signal to processor. Sending maybe implemented by enabling access for the processor to a memory addressin which the received signal is stored. When the audio sensor is notdirectly connected to the processor, sensing the received signal may beimplemented via a wired or wireless cable. In some cases, the collectedsignals are stored in a memory address known to the processor andaccessed by the processor.

Step 130 discloses receiving the signal by processor. The signals may bereceived by a memory module inside the processor or accessed by theprocessor when stored in a memory module in the system.

Step 140 discloses the processor loading predefined patterns of thefrequency signature from the memory unit of the system or from a remotedevice, such as an online server. The predefined patterns may beassociated with a specific object. The predefined patterns provideinformation as to the frequencies in which the audio is emitted due tothe movement of a specific object. The memory may comprise multiplefrequency patterns, each pattern of the multiple frequency patterns isassociated with a specific object. The processor may convert the audiosignals to the frequency domain using known methods, such as theDiscreate Fourier transform, its FFT implementation, wavelet functionsand the like.

Step 150 discloses the processor checking if the received signalincludes at least one predefined pattern associated with the specificobject. The processor may compare the pattern or patterns stored in thememory module of the system, or a memory module stored in a remotedevice, with the patterns extracted from the audio signals. Thecomparison may be updated after every set of signals sampled by theaudio sensor. In some exemplary cases, the system is configured toestimate hit or miss of a plurality of different objects havingdifferent frequency signatures. In such case, the multiple frequencysignatures are stored in the memory module of the system, and the systemcompares the collected audio signals with the multiple frequencysignatures in order to identify the specific object type of the multipleobj ects.

Step 155 discloses tracking the predefined pattern over time. That is,the frequency spectrum of the audio signals is collected over time, toidentify and compute changes in the frequency, as disclosed in step 160.Step 165 discloses predicting a minimal distance between the object andthe target based on the rate of change in the frequency of the audioemitted due to the object's movement. In one exemplary case, an objectis directed towards a target having an initial velocity of at 17 metersper second and having an audio signal at about 3000 Hz generated due tothe object's movement. When the maximum rate of change is 8300 Hz/sec,the minimal distance between the object and the target would be 15centimeters. When the minimal the maximum rate of change is 3700 Hz/sec,the minimal distance between the object and the target would be 40centimeters. Step 165 discloses emitting indication according to minimaldistance between the object and the target. The indication may be audio,light, vibration, smell, and the like.

It should be noted that the system may define multiple radii for aspecific target, each radius of the multiple radii is associated with adifferent rate of change in the frequency of the audio signal emitteddue to movement of a specific object or object type. Such radiuses maybe 0.2 m, 0.4 m, 0.6 m, 0.8 m. This way, the system may compute whetherthe object is within a range of 0.4 m but outside the range of 0.2 m anddetermine a range of distance from the audio sensor. For example, therange of distance may be from 0.2 meters to 0.4 meters.

In some exemplary cases, the system is configured to estimate distancebetween the target for multiple object types having different frequencysignatures. This way, the system identifies the object type and thenestimates whether the object type hit or missed the target. The systemthen logs the hit or miss in a memory module. The system may alsoestimate a range of distance from the target as explained above. Thesystem may then send a performance report to one or more electricaldevices based on the object types and the hit/miss and/or distance fromtarget. In some cases, the system may generate multiple reports, basedon the object types, and send the reports to electrical devicesassociated with the object type.

FIG. 16 shows a method for estimating a change in frequency of the audiosignal emitted due to and during the object's movement based on audiosignals, according to exemplary embodiments of the present invention.

Step 210 discloses defining a distance between the object and the audiosensor that qualifies as a hit. Such defining may be performed usinginformation inputted via a user's interface accessed by a user of thesystem, for example by manipulating buttons or a touch screen on thesystem, via a mobile phone, a personal computer, tablet, laptop, and thelike. The user may control an array of targets and assign a differentdistance to be defined as a hit radius for each target or for alltargets at once. For example, a training assembly, in which 5 targetshave a range of 5 centimeters that qualifies as a hit and 3 targets havea range of 25 3 centimeters that qualifies as a hit. The distancedefined as hit may be adjusted according to environmental measurementsor information, such as user's height, weight, terrain in which thesystem is placed, weather, light, and the like. In some exemplary cases,the distance defined as hit may be adjusted automatically based onmeasurements, such as environmental measurements, audio signals and thelike.

Step 220 discloses converting audio signals to the frequency domain.Such conversion may be performed using the Fourier transform. The audiosensor may sample 2,000-50,000 samples per second and send 20-120samples to the processor. The audio sensor samples the audio signals inresponse to the processor's command and terminates sampling upon atermination command from the processor.

Step 230 discloses performing time domain analysis or a frequencyanalysis to match the object type with the collected audio signal. Thefrequency analysis determines the frequency pattern of the audio emitteddue to the object's movement. For example, which local-maximafrequencies are detected, the amplitude in each frequency and the like.

Step 240 discloses updating the object's frequency analysis insubsequent groups of samples. For example, in the first run, theprocessor analyzes samples 1-120 and in the second run the processoranalyses samples 121-240. There can be an overlap between groups, forexample, in the first run, the processor analyzes samples 1-128 and inthe second run the processor analyzes samples 65-193.

Step 245 discloses identifying the rate of frequency change of the audiosignal's frequency spectrum, thereby computing the minimum distance ofthe object from the audio Sensor.

Step 250 discloses determining the distance between the location inwhich the object ended its movement and the target. Such determinationis based on the timing in which the object ended its movement. Thisprocess comprises computing a time in which object ended its movement.Such time is detected when the audio signal ceases to include theobject's frequency signature. Then, the system has the time durationbetween the time stamp in which the object was at minimal distance tothe target and the time when the object stopped moving. Determining thedistance may be performed by multiplying the time duration with a knownvelocity of the object, for example the object's initial velocity incase the object was fired at a known initial velocity.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives,modifications, and variations will be apparent to those skilled in theart. Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent, or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting.

1. A method for estimating hit or miss of an object directed towards atarget, comprising: collecting an audio signal over time by an audiosensor located on, inside or near the target, said audio signal isdefined by a set of frequencies; identifying changes in the set offrequencies over time; predicting a minimal distance between the objectand the audio sensor based on the changes in set of frequencies overtime; emitting an indication according to the minimal distance betweenthe object and the audio sensor.
 2. The method of claim 1, furthercomprising identifying that the object is directed towards the target bycomparing a pattern from the audio signal with a list of predefinedpatterns stored in a computerized memory.
 3. The method of claim 2,wherein each of the predefined patterns provides information as tofrequencies in which audio is emitted due to the movement of a specificobject, wherein identifying the object based on a frequency patternassociated with the object in the computerized memory.
 4. The method ofclaim 1, further comprising estimating hit or miss of a plurality ofdifferent objects having different frequencies.
 5. The method of claim1, further comprising computing a distance between the object's hitlocation and the target and determining a hit or miss of the object inthe target by comparing the computed distance and a threshold distance.6. The method of claim 5, wherein computing the distance between theobject's hit location and the target is based on the timing in which theobject ended its movement, said end of the object's movement is detectedwhen the audio signal ceases to include the object's frequencysignature.
 7. The method of claim 1, further comprises defining a rangeof distances from the audio sensor that qualifies as a hit, anddetermining a hit in case the distance between the hit location and theaudio sensor is smaller than the range.
 8. The method of claim 7,further comprises defining multiple radii from the audio sensor anddetermining two radii that define the distance between the object andthe audio sensor.
 9. The method of claim 1, further comprises defining adistance between the object and the audio sensor that qualifies as ahit.
 10. The method of claim 9, further comprises adjusting the distancebetween the object and the audio sensor that qualifies as a hit based onenvironmental measurements.
 11. The method of claim 1, further comprisesdetermining the distance between the location in which the object endedits movement and the target.
 12. The method of claim 11, furthercomprises detecting that the audio signal ceases to include the object'sfrequency signature; computing a time duration elapsing between a timestamp in which the object was at the minimal distance from the audiosensor and the time of detecting that the audio signal ceases to includethe object's frequency signature; multiplying the time duration with aknown or calculated velocity of the object.
 13. The method of claim 1,wherein the indication is emitted by at least one of light, sound, RF,and vibration.
 14. The method of claim 1, further comprises creating atracking log, said tracking log comprises the object's location and thedetected frequencies over time.
 15. The method of claim 1, whereinpredicting the minimal distance between the object and audio sensor isperformed before the object reaches the minimal distance.